(CBS/AP) LITTLE FALLS, Minn. - Byron Smith, a 64-year-old man, will be arraigned on Monday after police say they found the bodies of two teenage cousins who went missing on Thanksgiving Day in the basement of his central Minnesota home.

Little Falls school officials identified the victims as 18-year-old Haile Kifer and her 17-year-old cousin, Nicholas Brady. Smith reportedly told police he fatally shot the teenagers during a break-in, but
authorities said his actions exceeded reasonable self-defense.

Police said Smith was held in custody on Sunday, and they expect he will be charged with second-degree murder on Monday.

The Minneapolis Star-Tribune reported that about 200 people gathered Sunday night for a vigil at Little Falls High School for Kifer and Brady. Mourners remembered both as athletic and friendly.

Morrison County deputies visited Smith's home Friday afternoon on a suspicious activity call. They said he immediately confessed to shooting two people the previous day around noon. Deputies found the bodies in the basement.

The suspect's brother, Bruce Smith, told the Tribune that several break-ins left his brother feeling vulnerable and afraid, and that the shootings made him upset and unsure how to react.

"Put yourself in his shoes after you shoot two people in your basement," Bruce Smith told the newspaper Sunday. "How are you going to react?"

Morrison County Sheriff Michel Wetzel said Byron Smith claimed the teenagers broke into his home. But Wetzel said circumstances at the scene led investigators, including some from the state Bureau of Criminal Apprehension, to believe that his actions were in excess of simple self-defense.

Kifer was a senior at Little Falls High School. Superintendent Stephen Jones said she competed in gymnastics and swimming and helped manage the boys' wrestling team. Brady attended the same school and later transferred to nearby Pillager High School.

Jones said grief counselors will be on hand Monday even though students have a scheduled day off. Students and their parents will be invited to come to school and talk about what happened. He said more counselors will be in place on Tuesday when all students return; Pillager High School also planned to have counselors available.